1. Field of the Invention
The present invention relates generally to apparatus for rebuilding worn machine elements by depositing and welding build-up metal thereon, and more particularly to an improved apparatus for cooling rotary machine components of such elements under deposition of build-up metal on the worn surface thereof for such re-building purposes.
2. The Prior Art
It is common practice to re-build various worn machine components by depositing hard build-up metal onto the worn surface of the machine elements preparatory to another extended period of use. Track rollers for engaging tracks may be considered as a typical example of such a machine element which may be re-built in this manner. In conventional practice for building-up metal onto the worn parts of track rollers, the track rollers are completely disassembled and the build-up metal is deposited onto the worn surface of the disassembled roller rims. However, this technique is not practical, because the temperature of the roller rim is elevated to a heat distortion level during the course of applying the build-up metal. Thus, the welding operation must be stopped after each single loop of the build-up metal is deposited onto the worn surface of the rotary machine element, and it is removed from the welding apparatus for cooling, or the welding operation of the build-up metal must be stopped by halves, such that the re-building operation may be shifted to another machine element while the first is cooling. Also, disassembling and re-assembling of the component parts of the track rollers is required according to past practice, which results in a considerable decrease of the working efficiency.
Another previously known technique for building-up such track rollers involves placing the roller approximately half-way into a water bath as it is in an assembled condition. However, by this technique, submerged arc welding may not be practical, and the welding areas are rendered too cool by immersion in the water bath to use a welding rod which requires preheating and gradual cooling. Also, this technique involves difficulties in the welding operation resulting from the necessity of shielding and the generation spatter and the like.
Under these circumstances, the present inventors have proposed an improved apparatus as disclosed in the specification of U.S. Pat. No. 3,895,209. This improved apparatus, capable of overcoming the aforementioned problems or drawbacks of the prior art, on the other hand poses various problems as follow.
Namely, this apparatus requires a specific cylinder incorporating a hollow rod, for holding the track rollers. At the same time, the apparatus has a complicated construction consisting of an impractically large number of parts. In addition, if the circulation of the cooling water is stopped soon after the completion of the build-up welding, the non-metallic parts such as "O" rings incorporated in the roller may be burnt down due to the residual high temperature of the roller. To avoid this, it is necessary to continue the circulation of the cooling water for at least several minutes after the completion of the welding. This considerably deteriorates the efficiency of operation of the apparatus. Further, a troublesome step of blowing air into the cooling system is required for expelling the cooling water, when the track rollers are demounted from the apparatus.
Accordingly, it is an object of the present invention to provide a cooling apparatus for permitting a worn rotary machine element to be built-up without disassembling the machine element, thereby greatly increasing the working efficiency of the re-building operation.
Another object of the present invention is to provide a cooling apparatus for permitting a worn rotary machine element to be built-up without threat of heat distortion of an internal structure of the machine element, such as seals and the surface of the machine element on which the build-up metal is to be deposited by welding.
Still another object of the present invention is to provide a cooling apparatus for enabling a worn rotary machine element to be automatically or semi-automatically built-up by arc welding, submerged arc welding, open, gas shield and so on, while the machine element is continuously rotated at a relatively slow speed in synchronism with the deposition of build-up metal onto the worn surface of the machine element.
A further object of the invention is to provide an apparatus which permits the removal of the track rollers immediately after the completion of welding, without causing any leak of cooling water.
A still further object of the invention is to provide an apparatus having a track-roller holding mechanism which is simple, small-sized and safe.